Abstract

If unique hues have special status in phenomenological experience as perceptually pure, it seems reasonable to assume that they are represented more precisely by the visual system than are other colors. Following the method of Malkoc et al. (J. Opt. Soc. Am. A 22, 2154 [2005]), we gathered unique and binary hue selections from 50 subjects. For these subjects we repeated the measurements in two separate sessions, allowing us to measure test–retest reliabilities (0.52≤ρ≤0.78; p≪0.01). We quantified the within-individual variability for selections of each hue. Adjusting for the differences in variability intrinsic to different regions of chromaticity space, we compared the within-individual variability for unique hues to that for binary hues. Surprisingly, we found that selections of unique hues did not show consistently lower variability than selections of binary hues. We repeated hue measurements in a single session for an independent sample of 58 subjects, using a different relative scaling of the cardinal axes of MacLeod–Boynton chromaticity space. Again, we found no consistent difference in adjusted within-individual variability for selections of unique and binary hues. Our finding does not depend on the particular scaling chosen for the Y axis of MacLeod–Boynton chromaticity space.

J. Mollon and C. Cavonius, “The chromatic antagonisms of opponent process theory are not the same as those revealed in studies of detection and discrimination,” in Colour Vision Deficiencies VIII, G. Verriest, ed. (Junk, 1987).

K. A. Jameson, “Where in the World Color Survey is the support for the Hering primaries as the basis for color categorization?” in Color Ontology and Color Science, J. Cohen and M. Matthen, eds. (MIT, 2010), pp. 179–202.

Cárdenas, L. M.

Cavonius, C.

J. Mollon and C. Cavonius, “The chromatic antagonisms of opponent process theory are not the same as those revealed in studies of detection and discrimination,” in Colour Vision Deficiencies VIII, G. Verriest, ed. (Junk, 1987).

K. A. Jameson, “Where in the World Color Survey is the support for the Hering primaries as the basis for color categorization?” in Color Ontology and Color Science, J. Cohen and M. Matthen, eds. (MIT, 2010), pp. 179–202.

Mollon, J.

J. Mollon and C. Cavonius, “The chromatic antagonisms of opponent process theory are not the same as those revealed in studies of detection and discrimination,” in Colour Vision Deficiencies VIII, G. Verriest, ed. (Junk, 1987).

Other (7)

K. A. Jameson, “Where in the World Color Survey is the support for the Hering primaries as the basis for color categorization?” in Color Ontology and Color Science, J. Cohen and M. Matthen, eds. (MIT, 2010), pp. 179–202.

J. Mollon and C. Cavonius, “The chromatic antagonisms of opponent process theory are not the same as those revealed in studies of detection and discrimination,” in Colour Vision Deficiencies VIII, G. Verriest, ed. (Junk, 1987).

Figures (4)

Stimuli. Panel (a) shows the range of chromaticities, in our scaled version of MacLeod–Boynton chromaticity space, from which the stimuli were drawn. Panel (b) indicates the two frames of a trial. In frame 1, 25 colored segments were presented whose range chromaticities spanned the full hue circle shown in panel (a). In frame 2, the 25 selectable segments had chromaticities from a quarter of the full hue circle, according to the subject’s selection on frame 1. For reference, an inner annulus was presented of 25 unselectable segments with chromaticities that ranged over the full hue circle.

(a) Histograms of average hue selections. Mean selections are indicated by the dashed lines, and 95% confidence intervals by the solid arcs. Results are colored according to the hue. (b) Test–retest reliabilities. Median hue selections from session 2 are plotted against median selections from session 1. Correlation coefficients are given in Table 1. (c) Polar plot of standard deviation of hue selections (r) as a function of group mean hue selection (θ) for session 1. Group mean selections of each hue are the mean of median hue selections of 50 subjects. The standard deviation is the mean standard deviation of 50 subjects, with 10 selections for each hue. The ellipse is the best-fitting ellipse through the data. (d) Polar plot of standard deviation of hue selections (r) as a function of median hue selections (θ) for session 2. (e) Mean residuals (over 50 subjects) of the positions of each hue from the best fitting ellipse for each subject. If the residual is negative, the standard deviation of hue selections is inside the ellipse and therefore smaller than expected. If the residual is positive, the standard deviation of hue selections is outside the ellipse and therefore greater than expected. Residuals for session 1 are shown by black borders, and residuals for session 2 by gray borders. Bars representing results for the eight hues are colored accordingly. Error bars are 95% confidence intervals on the mean residuals.

Chromaticities of selectable segments in Experiment 2 compared to those of Experiment 1. The scaling factor applied to the L/(L+M) axis of MacLeod–Boynton chromaticity space was smaller in Experiment 2 (2.8) than in Experiment 1 (3.88), so the locus of chromaticities presented in Experiment 1 appears as an ellipse in this figure (dashed line). The chromaticities for each of the three saturations are shown separately, and the central black dot indicates the chromaticity of D65, which was the chromaticity of the surround.

(a) Distributions of median hue selections measured in Experiment 2 for the three different saturations. Selections for saturation 1 are plotted in the outer annulus, selections for saturation 2 in the middle annulus, and selections for saturation 3 in the inner annulus. Distributions for each hue are colored accordingly, and mean hue selections are indicated by the dashed lines. 95% confidence intervals are indicated by the solid arcs. (b) Best-fitting ellipses through a polar plot of the standard deviation of hue selections (the mean, over 58 subjects, of the standard deviation of the 10 selections for each hue) (r) against the mean hue selection (of median selections of 58 subjects) (θ). (c) Mean residuals. Residuals are the distance of each hue from the best-fitting ellipse [to standard deviation of hue selections (r) as a function of median hue selection (θ)] for each subject. Negative residuals indicate that the standard deviation of selections for that hue is inside the best-fitting ellipse, and so is lower than expected. Positive residuals indicate that the standard deviation of selections for that hue is outside the best-fitting ellipse, and so is greater than expected. Bars are colored according to the hue. For each triplet of bars, results for saturation 1 are left, results for saturation 2 are center, and results for saturation 3 are right. Error bars are 95% confidence intervals on the means.